Some links on this page are affiliate links. If you buy through them, Dubspot may earn a commission at no extra cost to you. It never affects our scores or what we recommend — read our policy.
Kazrog Vac Rac TSL Puts Boutique Tube Opto Limiters in a Plugin
Kazrog Vac Rac TSL models four Inward Connections tube optical limiters with ratios to 12:1, THD drive, M/S and sidechain filters. $49.99 intro, from $79.99.
E
Elena Marsh
October 29, 2026 · 7 min read
Kazrog has released Vac Rac TSL, the official plugin version of the Vac Rac tube optical compressor/limiters hand-built by Steve Firlotte of Inward Connections. Firlotte worked with Kazrog directly on the emulation, which models four hardware units in one plugin. It is $49.99 at launch in Kazrog's store, down from $79.99, with a free, time-unlimited demo.
At a glance: optical gain reduction through a tube signal path; TSL-5, TSL-4 and TSL-3 voicings plus a blend for the transformerless TLM-1; ratios from 2:1 to 12:1 and up to 40 dB of reduction per channel; THD control from warmth to heavy distortion; two independent channels with dual-mono, stereo-link and mid/side modes; sidechain filters, wet/dry mix and VU meters. VST, VST3, AU, AAX and LV2 on Mac, Windows and Linux, no iLok. $49.99 intro (regular $79.99) at Kazrog.
What is Vac Rac TSL?
Most optical compressor plugins copy one vintage box, the Teletronix LA-2A, and give you two knobs. The Vac Rac is a different animal. Inward Connections builds them by hand today, and rather than clone a single classic design, Firlotte draws on the history of tube optical limiters and makes his own tonal choices. Kazrog set out to capture the way the TSL's tubes "bloom" under program material, and pitches the plugin as part compressor, part tube saturation box.
Kazrog modelled four specific units. The TSL-5 and TSL-4 come from producer Devin Powers' collection, the TSL-3 from Grammy winner Ross Hogarth's own unit, and the TLM-1 path from Grammy winner JJ Blair's original Vac Rac. Our Vac Rac TSL database entry tracks its price and alternatives.
What it does
Three tube voicings and a TLM-1 blend
You pick the TSL-5, TSL-4 or TSL-3 voicing, then blend in the transformerless TLM-1 signal path. That lets you mix the transformer-based TSL voicings with the TLM-1's transformerless path in a single instance, without stacking plugins.
Real ratio and reduction controls
Unlike an LA-2A-style two-knob design, each channel has its own Ratio (2:1 to 12:1), Reduction (up to 40 dB) and Makeup Gain, plus a Detector HPF so low end does not drive the compression. Gentle ratios level a vocal; 12:1 with heavy reduction turns it into a limiter for peaks or obvious, pumping bus compression.
THD: compressor and tube drive in one
The THD control pushes the tube stages from subtle warmth to extreme distortion. On a bass or drum bus you can use Vac Rac TSL as a saturation box with compression behind it, or keep THD low for clean levelling.
Two channels, M/S and parallel
The two-channel layout runs dual mono, stereo linked or mid/side, so you can compress the centre of a mix harder than the sides. Sidechain high-pass (10 Hz to 250 Hz) and low-pass filters, a wet/dry mix for parallel compression and switchable VU meters (gain reduction or output) on each channel complete the set.
Analog Entropy and oversampling
Kazrog's Analog Entropy models component tolerances, so the two channels differ slightly as real hardware does. Oversampling goes up to 64x in real time and 256x offline, with selectable filter taps for when you push THD hard.
Vac Rac TSL specifications
| Spec | Detail |
|---|---|
| Type | Tube optical compressor/limiter, two channels |
| Units modelled | TSL-5, TSL-4 (Devin Powers), TSL-3 (Ross Hogarth), TLM-1 transformerless path (JJ Blair) |
| Ratio | 2:1 to 12:1 |
| Gain reduction | Up to 40 dB per channel |
| Modes | Dual mono, stereo link, mid/side |
| Sidechain | High-pass 10 Hz to 250 Hz, low-pass filter |
| Extras | THD drive, wet/dry mix, VU meters (GR or output), Analog Entropy |
| Oversampling | Up to 64x real time, 256x offline |
| Mac | macOS 10.13 or later; VST, AU, AAX; Universal Binary (Apple Silicon and Intel) |
| Windows | Windows 10 or later recommended; VST, AAX |
| Linux | VST3, VST2, LV2 |
| Licence | Perpetual, multiple devices, no iLok |
| Demo | Time-unlimited; random silences and no preset saving |
Vac Rac TSL vs LA-2A Collection vs CLA-2A
All three are tube optical compressors at a similar price tier. Rival prices are Plugin Boutique's on 29 October.
| Kazrog Vac Rac TSL | UAD Teletronix LA-2A Collection | Waves CLA-2A | |
|---|---|---|---|
| Price now | $49.99 intro (Kazrog store) | $39 at Plugin Boutique to 31 Oct | $34.99 at Plugin Boutique to 1 Nov |
| Regular price | $79.99 | $149 | $149 |
| Hardware | Four Inward Connections Vac Rac units | LA-2A Silver, LA-2A Gray, LA-2 | Teletronix LA-2A |
| Ratio control | 2:1 to 12:1 | Compress/Limit switch | Compress/Limit switch |
| Drive | THD control | No | No |
| Stereo modes | Dual mono, link, mid/side | Stereo | Stereo |
| Licence | No iLok, Linux support | iLok account | Waves licence |
Which to pick: the LA-2A Collection is the authentic classic and, at $39 this week, the cheapest way into tube opto sound. CLA-2A is the simplest. Vac Rac TSL is the one to choose if you want more control than two knobs give you: real ratios, M/S, sidechain filtering and a drive stage, at a price that is still low. For the high end of tube opto, the Tube-Tech CL 1B mk II is a further step up in cost.
Who Vac Rac TSL is for
- Vocal and bass mixers who like LA-2A-style levelling but want a ratio control and a detector filter.
- Mix-bus and drum-bus users who want compression and tube saturation in one plugin, with parallel blend.
- Linux producers, since VST3, VST2 and LV2 builds are included at no extra cost.
Who should skip it: if you want a fast, transparent or surgical compressor, an opto design is the wrong tool; look at our best mastering plugins guide for clean dynamics. And if you already own an LA-2A emulation you love and never touch more than two knobs, the extra features may not matter.
How much does Vac Rac TSL cost?
Vac Rac TSL is $49.99 in Kazrog's store, down from its regular $79.99. Every Kazrog plugin comes with a perpetual licence for multiple devices, with no iLok, challenge/response keys or dongles. The free demo on Kazrog's site never expires, but it drops to silence now and then and will not save presets. Buying and reinstalling through the Kazrog Plugin Manager removes those limits. For more colour options alongside it, see our best saturation plugins of 2026.
FAQ
What is Vac Rac TSL?
Kazrog's official plugin emulation of the Inward Connections Vac Rac tube optical compressor/limiters, developed with Vac Rac builder Steve Firlotte. It models the TSL-5, TSL-4, TSL-3 and the TLM-1 transformerless path.
Is Vac Rac TSL an LA-2A clone?
No. It is an optical tube compressor like the LA-2A, but it models modern hand-built Vac Rac units and adds a ratio control from 2:1 to 12:1, up to 40 dB of reduction, THD drive, mid/side and sidechain filters.
Does Vac Rac TSL need an iLok?
No. Kazrog licences are perpetual, cover multiple devices and need no iLok, dongle or challenge/response key.
What formats does Vac Rac TSL support?
VST, AU and AAX on macOS 10.13 or later (Apple Silicon and Intel), VST and AAX on Windows, and VST3, VST2 and LV2 on Linux.
Is there a Vac Rac TSL demo?
Yes. The demo has no time limit, but it outputs random silences and disables preset saving until you buy.
